1. Field
The following description relates to wireless communications, and more particularly, to signal amplification in a wireless transmitting apparatus.
2. Description of the Related Art
Recent wireless communication technology has achieved a high data transmission speed. Accordingly, the wireless communication technology has shifted from a code division multiple access-(CDMA-)based system to a system such as an orthogonal frequency division multiplexing (OFDM) that uses multiple sub-carrier modulation scheme. For example, systems, such as Worldwide Interoperability for Microwave Access (WiMAX), wireless broadband (WiBro), 3rd generation long term evolution (3G LTE), and the like, uses an OFDM modulation scheme.
In such an OFDM system, the summation of sub-carriers causes increase of a peak to average power ratio (PAPR). Hence, various methods for increasing efficiency in a transmitting apparatus have been discussed. As one example, there is an envelope elimination and restoration (EER) method in which a phase signal is input to a power amplifying apparatus using polar coordinates, and envelope information is applied to a bias unit of the power amplifying apparatus.